1. Technical Field
The present invention relates to polyester-based plastic floor tiles, and more particularly, to a halogen-free, heavy metal-free, and volatile organic compound-free polyester-based plastic floor tile excellent in both physical and chemical properties, such as excellent in higher resistance to wear and tear, better tensile strength, more preferable resistance to both lit cigarette e and solvents.
2. Description of Related Art
polyvinyl chloride-based (abbreviated as PVC-based) plastic floor tiles contain halogen and heavy metals and are seldom environment-friendly so that PVC-based plastic floor tiles are not recommended for recycling. The toxic dioxin gas produced during the process of incineration of discarded PVC-based plastic floor tiles is hazardous to human beings' health. Hence, the ban on PVC-based plastic floor tiles is increasingly tight.
By contrast, no dioxin is produced during the process of incineration of discarded polyolefin resin floor tiles, such as PE-based plastic floor tiles and PP-based plastic floor tiles. But polyolefin resin floor tiles have disadvantages, including difficult to print, difficult to adhere, and difficult to mount and process. Moreover, polyolefin resin is disadvantageously characterized by high fluidity; as a result, not only are laminated finished products made of polyolefin resin predisposed to uneven thickness, but the material of the polyolefin resin floor tile is also susceptible to deterioration when subjected to UV irradiation.
More detailed speaking, during the process for producing polyolefin resin floor tiles, deformation and printed pattern-related defects as well as having uneven thickness are likely to happen to laminated finished products made of polyolefin resin in the course of heating lamination, and more particularly, the polyolefin resin floor tiles are susceptible to deterioration if subjected to UV irradiation.
Hence, the polyolefin resin floor tiles during their production process must undergo processes, such as modification, electrical corona treatment, and surface treatment, thereby taking time, incurring costs, and causing high energy consumption related to raw materials for use in manufacturing polyolefin resin. Particularly, the produced polyolefin resin floor tile because of poor weatherability has a short service life and also has a negative effect on environmental protection.
With regard to polyethylene terephthalate-based (abbreviated as PET-based) plastic floor tiles made of laminated polyester PET films or sheets, conventional polyester PET resin due to having high crystallization displays high fluidity when heated and melted, resulted in that polyester PET resin is unfit for open-style calendaring machine, but is usually processed with an extruder, to produce a polyester PET film or sheet. For example, U.S. Pat. No. 5,998,005 and U.S. Pat. No. 6,068,910 disclose that, during a speedy production process for producing polyester PET films or sheets, a calendaring machine is likely to get stuck and thus become ineffective in shaping the polyester PET products, and thus the calendaring machine finally sustains a high load to shorten the service life of a transmission shaft for use in the calendaring machine thereof.
Further, due to having high crystallization but low crystallization speed, both PET and polyester if used to produce PET or polyester films or sheets are difficult to shape and process, conversely require a high molding temperature and a long production cycle, and also feature poor impact performance. Although U.S. Pat. No. 7,438,841 discloses a polyester composite suited for use in calendaring machine, the polyester composite manifests low thermal resistance and thus its crystals gradually decompose at high temperature to thereby make the calendaring machine stuck; as a result, its processability is greatly compromised in a manner to eventually reduce both the mechanical strength and the resistance to wear and tear of polyester finished products.
When a film or a sheet completely produced through a calendaring machine should have been processed with multiple steps of extension, including an embossed process, a cooled process and a winded process, leading to the produced film or sheet with high contraction rate and poor size stability. If multiple layers of films or sheets with different contraction rates are hot-pressed and laminated to produce laminated floor tiles, the finished products will be compromised in terms of consistency of appearance and thickness. Accordingly, both PET and polyester have long been regarded by persons skilled in the art as ineligible to be calendered for forming sheet-like materials.
Moreover, conventional PVC-based floor tiles, polyolefin resin-based floor tiles, and polyester PET-based plastic floor tile demonstrate low resistance to lit cigarettes and thus are likely to be defaced when the lit cigarettes are put, or stubbed out, on the aforesaid floor tiles.